From e5a592162289732cfc835057b6ab66c550da9b88 Mon Sep 17 00:00:00 2001
From: David Rose <david@ddrose.com>
Date: Wed, 14 Mar 2001 20:26:54 +0000
Subject: [PATCH] *** empty log message ***

---
 panda/src/graph/wrt.I | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/panda/src/graph/wrt.I b/panda/src/graph/wrt.I
index 94a52b5f97..b429ab6cd7 100644
--- a/panda/src/graph/wrt.I
+++ b/panda/src/graph/wrt.I
@@ -779,6 +779,25 @@ cached_wrt_subtree(NodeRelation *arc, Node *to, UpdateSeq as_of, UpdateSeq now,
       result.write(wrt_cat.spam(false), 2);
     }
 #endif
+
+    if (to->get_num_parents(graph_type) != 1) {
+      // Oops!  We *don't* have exactly one parent.  This means our
+      // cache is stale in some surprising way.  To recover, we'll
+      // force a recompute of the cache by asking for the wrt() from
+      // the very latest timestamp.
+
+      // This, of course, assumes we haven't just asked for the wrt()
+      // from the very latest timestamp.
+#ifndef NDEBUG
+      if (wrt_cat.is_info()) {
+	wrt_cat.info()
+	  << "Recovering from stale cache.\n";
+      }
+#endif
+      nassertr(as_of != UpdateSeq::fresh(), NULL);
+      return cached_wrt_subtree(arc, to, UpdateSeq::fresh(), 
+				UpdateSeq::fresh(), result, graph_type);
+    }
     
     nassertr(to->get_num_parents(graph_type) == 1, NULL);
     NodeRelation *to_arc = to->get_parent(graph_type, 0);